Identification of S-RNase Genotypes of 65 Almond [<i>Prunus dulcis</i> (Mill.) D.A. Webb] Germplasm Resources and Close Relatives

Self-incompatibility (SI) systems in plants prevent self-pollination and mating among relatives, enhancing genetic diversity in nature but posing challenges in almond production and breeding. S-allele composition alongside the flowering periods of these cultivars enables the anticipation of cross-compatibility and optimal cultivar combinations for the allocation of pollinating trees in production. In the current study, 65 materials containing 61 almond (Prunus dulcis) germplasm resources, of which two were hybrids and the remaining four were peach (Prunus persica) germplasms, were used for the S-RNase genotype. The results showed that 55 genomic samples were amplified by PCR to obtain double-banded types, which identified their complete S-RNase genotypes, while the rest of the samples amplified only a single band, identifying one S-RNase gene in the S gene. A total of 30 S-RNase genes were identified in Prunus dulcis, Prunus webbii, Prunus persica, Prunus armeniaca, Prunus salicina, and Prunus cerasifera. Sequence analysis revealed polymorphisms spanning from 313 to 2031 bp within the amplified fragment sequence. The S57-RNase gene exhibited the highest frequency at 31.75% among the identified materials, with S1S57, S10S57, and S7S57 being the predominant S genotypes. A new S-RNase gene, named S65, was identified with a sequencing length of 1483 bp. Its deduced amino acid sequence shared 98.24% similarity with the amino acid sequence of the S-RNase gene on GenBank, with the highest homology. Furthermore, according to the findings, 65 materials belong to eight S genotype cross-incompatibility groups (CIG) and one semi-compatibility or compatibility group (0). Among them, most of the seven main almond germplasm resources and 35 cultivars can be cross-pollinated. The results of the study can lay the foundation for pollinator tree allocation and breeding hybrid parent selection in almond production

荒漠河岸林植物木质部导水与栓塞特征及其对干旱胁迫的响应/Xylem hydraulic conductivity and embolism properties of desert riparian forest plants and its response to drought stress[J]

以同处于干旱区的塔里木河下游(铁干里克)和黑河下游(乌兰图格)断面为研究区,比较了荒漠河岸林主要建群种胡杨(Populus euphratica)、柽柳(Tamarix spp.)、疏叶骆驼刺(Alhagi sparsifolia)和花花柴(Karelinia caspia)在长期遭受不同干旱胁迫下的根、枝条木质部导水力和栓塞化程度的变化特征,并分析了木质部导水对干旱胁迫的响应及适应策略.结果表明:1)黑河下游荒漠河岸林植物的导水能力显著高于塔里木河下游,其中柽柳、胡杨、疏叶骆驼刺和花花柴根木质部的初始比导率(Ks0)分别高11.97、6.74、7.10和3.73倍,枝条的Ks0分别高9.48、3.65、2.07和1.88倍,地下水埋深导致的干旱胁迫程度不同是诱发荒漠植物导水能力差异的根本原因；2)柽柳耐干旱能力最强,适应范围较宽,而花花柴、疏叶骆驼刺的耐旱性相对较弱,适生范围较窄,这可能与植物的根系分布有关；3)干旱胁迫较轻时,枝条木质部是荒漠河岸林植物水分传输的主要阻力部位,干旱胁迫严重时,根木质部是限制植株水流的最大阻碍部位；4)荒漠河岸林植物主要通过调节枝条木质部的水流阻力来适应干旱胁迫,且其适应策略与干旱胁迫程度有关,干旱胁迫轻时,植物通过限制枝条木质部水流来协调整株植物的均匀生长;干旱胁迫严重时,植物通过牺牲劣势枝条、增强优势枝条水流来提高植株整体生存的机会